Key Facts

  • Categorized as a Apollo-class Asteroid
  • Comparable in size to the Golden Gate Bridge (0.78 km diameter)
  • Will pass within 10,656,479 km of Earth in 2022
  • Classified as a Near Earth Asteroid (NEA)
  • Classified as a Potentially Hazardous Asteroid (PHA)
  • See orbit simulation


Didymos is a small asteroid whose orbit crosses the orbit of Earth. NASA JPL has classified Didymos as a "Potentially Hazardous Asteroid" due to its predicted close pass(es) with Earth.

Didymos orbits the sun every 769 days (2.11 years), coming as close as 1.01 AU and reaching as far as 2.27 AU from the sun. Didymos is about 0.8 kilometers in diameter, making it larger than ~97% of asteroids but small compared to large asteroids, comparable in size to the Golden Gate Bridge.

The rotation of Didymos has been observed. It completes a rotation on its axis every 2.26 hours.

Didymos's spectral type None (Tholen) / Xk (SMASSII) indicates that it is likely to contain iron, nickel, and cobalt.

Close Approaches

Didymos's orbit is 0.04 AU from Earth's orbit at its closest point. This means that there is a wide berth between this asteroid and Earth at all times.

Didymos has 8 close approaches predicted in the coming decades:

Date Distance from Earth (km) Velocity (km/s)
Oct. 4, 2022 10,656,479 5.994
Oct. 20, 2062 7,427,722 5.141
Nov. 29, 2083 22,034,564 9.582
Sept. 19, 2102 22,793,097 9.158
Nov. 4, 2123 5,856,253 5.230
Dec. 2, 2144 26,654,808 10.557
Sept. 17, 2163 27,162,851 10.172
Oct. 14, 2184 8,589,293 5.439

Images and Observations

Didymos's orbit is determined by observations dating back to April 11, 1996. It was last officially observed on Jan. 21, 2023. The IAU Minor Planet Center records 3,121 observations used to determine its orbit.

Accessibility and Exploration

This asteroid is not considered a viable target for human exploration by the NHATS study.

Similar Objects

These objects have orbits that share similar characteristics to the orbit of Didymos:



   or view a random object

Orbital Elements

  • Epoch: 2460200.5 JD
  • Semi-major axis: 1.643 AU
  • Eccentricity: 0.3833
  • Inclination: 3.41°
  • Longitude of Ascending Node: 72.99°
  • Argument of Periapsis: 319.58°
  • Mean Anomaly: 152.7°

Physical Characteristics

  • Diameter: 0.78000 km
  • Magnitude: 18.11
  • Spectral type (SMASS): Xk

Derived Characteristics

  • Orbit Period: 769 days (2.11 years)
  • Avg. Orbit Speed: 23.24 km/s
  • Aphelion Distance: 2.27 AU
  • Perihelion Distance: 1.01 AU
  • Rotation Period: 2.26 hours
  • Approx. Composition: iron, nickel, and cobalt.

Map Comparison

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Orbit Simulation

Sky Map

The position of Didymos is indicated by a ◯ pink circle. Note that the object may not be in your current field of view. Use the controls below to adjust position, location, and time.

Size Rendering

The above comparison is an artistic rendering that uses available data on the diameter of Didymos to create an approximate landscape rendering with Mount Everest in the background. This approximation is built for full-resolution desktop browsers. Shape, color, and texture of asteroid are imagined.